Page 2 - May Newsletter

Crop Production By: Jeanne Falk Jones
Research on Tillage Intensity in Fallow in a Long-Term Wheat-Sorghum-Fallow Rotation
As we are looking at weed control in fallow this summer,
and CT from sorghum harvest through wheat planting.
you might be asking yourself about using tillage vs herbi-
The NT system exclusively used herbicides to control
cides and no-till and the yield effects of these practices.
weed growth during the fallow period. All tillage systems
This article covers results from a long-term research pro-
used herbicides for in-crop weed control.
ject at the K-State Southwest Research-Extension Center
Results and Discussion.
at Tribune. Authors of the research report are L.A. Haag,
Soil Water at wheat planting and at the following sor-
A. Burnett, D. Bond, J. Slattery, and A. Schlegel. You can
ghum planting. The amount of available water in the soil
see this research report and others from K-State at
profile (0–8 ft) at wheat planting varied greatly from year
www.newprairiepress.org and search for this title or
there is a direct link on the K-State Sunflower District
to year. In 2022, available soil water at wheat planting was
greater with NT (15.3 inches) than RT (12.5 inches) and CT
Agronomy website at www.sunflower.ksu.edu/agronomy.
(13.9 inches). Across the 22-yr study, available soil water at
Summary.
wheat planting was greatest for NT (8.44 inches) followed
This study was initiated in 1991 at the K-State Southwest
by RT (7.85 inches), and CT (6.72 inches). Similar to wheat,
Research-Extension Center near Tribune, KS. The purpose
the amount of available water in the soil profile at sor-
of the study was to identify the effects of tillage intensity
ghum planting varied greatly from year to year. In 2022,
on precipitation capture, soil water storage, and grain
available soil water at sorghum planting was greater with
yield in a wheat-sorghum-fallow rotation. Grain yields of
NT (7.8 inches) than RT (5.7 inches) and least with CT (5.3
wheat and grain sorghum increased with decreased till-
inches). On average, available soil water at sorghum plant-
age intensity in a wheat-sorghum-fallow (W-S-F) rotation.
ing was similar for NT and RT and about 2 inches greater
In 2022, available soil water at sorghum planting was
than CT.
greater for no-tillage (NT) than reduced tillage (RT),
which was greater than conventional tillage (CT). For
wheat there was a similar pattern as sorghum, with availa-
ble soil water at wheat planting being in the order of
NT>RT>CT. Averaged across the most recent 22 years of
the study, available soil water at wheat planting was 0.60
inch greater for NT than RT and approximately 1.7 inches
greater than CT. Average available soil water at sorghum
planting was greater in the order RT=NT>CT averaging 7.9
inches for RT and NT and 5.9 inches for CT. Averaged
across the past 22 years, NT wheat yields were 6 bu/a
greater than RT and 10 bu/a greater than CT. Averaged
across the past 22 years, sorghum yields with longterm NT
have been 57% greater than with RT (82 vs. 52 bu/a).
Experimental Procedures.
Research on different tillage intensities in a W-S-F rotation
at the Tribune, KS, unit of the Southwest Research-
Extension Center was initiated in 1991. The three tillage
intensities in this study are conventional (CT), reduced
(RT), and no-tillage (NT). The CT system was tilled as
needed to control weed growth during the fallow period.
On average, this resulted in 4 to 5 tillage operations per
year, usually with a blade plow or field cultivator. The RT
system originally used a combination of herbicides (1 to 2
spray operations) and tillage (2 to 3 tillage operations) to
control weed growth during the fallow period; however,
in 2001, the RT system was changed to using NT from
wheat harvest through sorghum planting (short-term NT)
Grain Yields. Wheat yields in 2022 were significantly re-
duced by hail damage and are not reported. Since 2001,
wheat yields have been depressed in 12 of 22 years, pri-
marily because of lack of precipitation, winterkill (2015),
viral disease (2017), and hail (2022). Reduced tillage and
NT increased wheat yields. On average, wheat yields were
10 bu/a higher for NT (33 bu/a) than CT (23 bu/a). Wheat
yields for RT were 4 bu/a greater than CT even though
both systems had tillage prior to wheat. Yields of NT were
significantly less than CT in only one year (2008) and RT in
2 of the 22 years (2001, 2008). Grain sorghum yields in
2022 were slightly above the long-term average. Sorghum
yields were 60% greater with NT than RT (108 vs. 67 bu/a)
while CT yields were the least (52 bu/a). The yield benefit
from reducing or eliminating tillage was greater for grain
sorghum than wheat. Grain sorghum yields for RT aver-
aged 20 bu/a more than CT, whereas NT averaged 30 bu/a
more than RT. For sorghum, both RT and NT used herbi-
cides for weed control in the wheat stubble post-harvest,
and in both the RT and NT systems, the sorghum was “no-
till” planted into wheat stubble. Using tillage in the sum-
mer-fallow period ahead of seeding wheat, while only re-
ducing wheat yields in a minor way, subsequent sorghum
yields were being significantly reduced. This yield benefit
with long-term vs. short-term NT (RT) has been observed
in most years since the RT system was changed in 2001.
Averaged across the 20 years, sorghum yields with long-
term NT have been 57% greater than RT (82 vs. 52 bu/a).
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